Roads deteriorate gradually over time – the surface gradually crumbles due to natural weathering and the aging process of bitumen, which becomes more brittle with age. The passage of vehicles – particularly heavy vehicles - can lead to cracking which then allows water into the road surface. In winter repeated cycles of freezing and thawing of the water under the surface leads to expansion, heaving the surface up and enlarging the crack, allowing more water to enter. This cycle repeats, increasing the size of the hole. Vehicle tyres entering a flooded hole also cause pressure waves which can further erode the road foundation, pushing loose material out of the hole deepening and widening it.

How to stop potholes forming:

Inspect surfaces regularly – a good programme of inspection, augmented by individual reports using tools like fillthathole.org.uk can help councils determine where the priority areas for repair are.

Keep roads well drained – clear ditches, culverts and drains regularly and engineer roads to be clear of standing water. Flooded roads can erode the surface and water to enter through cracks.

Ensure surfaces are watertight – regular maintenance can prolong the life of the road and ensure it remains watertight by sealing it with a thin layer of asphalt and chippings often described as ‘surface dressing’. Badly designed, however, this can make roads rougher.

Minimise utility works and check quality of repair – road works are often blamed for causing delays and congestion. They also lead to potholes forming as the opening of the road weakens the structure, often leading to potholes forming. Local authorities must also check up on the quality of the reinstated carriageway to ensure that the utility company’s contractor has done a decent job.

Regularly resurface – all roads will fail eventually. It is often much more expensive to continually repair a failing road than to undertake a full resurfacing.

Reduce traffic – the volume of traffic, particularly heavy vehicles, is the main cause of initial road surface failure. Restricting the use of large vehicles on minor roads can ensure that they stay in better condition for longer.